Serialization: Harden deserializeVar

Author: xymus

lib/Serialization/Deserialization.cpp

@@ -3810,14 +3810,22 @@ class DeclDeserializer {
       AddAttribute(new (ctx) HasStorageAttr(/*isImplicit:*/true));
 
     if (opaqueReturnTypeID) {
+      auto opaqueReturnType = MF.getDeclChecked(opaqueReturnTypeID);
+      if (!opaqueReturnType)
+        return opaqueReturnType.takeError();
+
       ctx.evaluator.cacheOutput(
           OpaqueResultTypeRequest{var},
-          cast<OpaqueTypeDecl>(MF.getDecl(opaqueReturnTypeID)));
+          cast<OpaqueTypeDecl>(opaqueReturnType.get()));
     }
 
     // If this is a lazy property, record its backing storage.
     if (lazyStorageID) {
-      VarDecl *storage = cast<VarDecl>(MF.getDecl(lazyStorageID));
+      auto lazyStorageDecl = MF.getDeclChecked(lazyStorageID);
+      if (!lazyStorageDecl)
+        return lazyStorageDecl.takeError();
+
+      VarDecl *storage = cast<VarDecl>(lazyStorageDecl.get());
       ctx.evaluator.cacheOutput(
           LazyStoragePropertyRequest{var}, std::move(storage));
     }